Terminal, Communication System, and Terminal Synchronization Method

The present technology relates to a communication system. More specifically, the present technology relates to a terminal in a communication system and a terminal synchronization method.

In a communication system including a plurality of terminals, there is known a technique for reducing power consumption by each terminal autonomously controlling start and pause. For example, a wireless communication system that controls a simple operation according to a remaining battery amount of a local station has been proposed (see, for example, Patent Document 1).

Patent Document 1: Japanese Patent Application Laid-Open No. 2013-030871

In the above-described conventional technique, each device controls the simple operation by its own determination, thereby reducing power consumption. However, in the control based on such an autonomous determination, there is a problem that total power consumption of the entire system cannot be considered, and a deviation in power consumption occurs between devices.

The present technology has been made in view of such a situation, and an object of the present technology is to equalize power consumption of each terminal by grasping a power supply state of each terminal, and to achieve power saving of the entire system in a communication system including a plurality of terminals.

The present technology has been made to solve the above-described problems, and a first aspect of the present technology is a terminal including: a power supply state determination information acquisition unit that acquires power supply state determination information for determining a power supply state of a local terminal, a power supply state determination information communication unit that performs communication for exchanging the power supply state determination information with another terminal, a representative terminal determination unit that determines a representative terminal on the basis of the power state determination information of the local terminal and the another terminal, a reference signal reception unit that receives a reference signal necessary for synchronization and generates time information in a case where the local terminal corresponds to the representative terminal, and a time information communication unit that transmits the time information to the another terminal in the case where the local terminal corresponds to the representative terminal, and receives the time information from the representative terminal in a case where the local terminal does not correspond to the representative terminal, a communication system, and a terminal synchronization method. This brings about an effect of suppressing the reception operation of the reference signal in terminals other than the representative terminal by transmitting the time information from the representative terminal that has received the reference signal to another terminal.

Furthermore, in the first aspect, the reference signal reception unit may receive a satellite signal as the reference signal and generate the time information in the case where the local terminal corresponds to the representative terminal. This brings about an effect of suppressing the reception operation of the satellite signal in the terminals other than the representative terminal.

Furthermore, in the first aspect, a sensor that acquires a sensing data signal, and a data signal transmission unit that transmits the sensing data signal after synchronization based on the time information is completed may be further included. This brings about an effect of transmitting the sensing data signal in a time-synchronized state.

Furthermore, in the first aspect, the power supply state determination information acquisition unit may acquire a value related to a power supply capacity obtained from a power supply of the local terminal as the power supply state determination information. In this case, the value related to the power supply capacity is a remaining power supply amount of the power supply of the local terminal. This brings about an effect of exchanging the value related to the power supply capacity between the terminals and determining the representative terminal.

Furthermore, in the first aspect, the power supply state determination information acquisition unit may acquire, as the power supply state determination information, a standby time required to receive the reference signal or the time information within a predetermined period. This brings about an effect of exchanging the standby time between the terminals and determining the representative terminal.

Furthermore, in the first aspect, the power supply state determination information acquisition unit may acquire, as the power supply state determination information, a value obtained by estimating a remaining amount of the power supply of the local terminal on the basis of a standby time required to receive the reference signal or the time information within a predetermined period. This brings about an effect of exchanging an estimated remaining power supply amount between the terminals and determining the representative terminal.

Furthermore, in the first aspect, a group terminal registration unit that registers identification information of the another terminal that forms a group may be further included, and the representative terminal determination unit may determine the representative terminal on the basis of the power supply state determination information of the local terminal and of the another terminal registered in the group terminal registration unit. This brings about an effect of determining the representative terminal between the terminals in the group.

1. First Embodiment (an example of exchanging a remaining power supply amount measured from a power supply between terminals) 2. Second Embodiment (an example of exchanging a standby time of time information and estimating a remaining power supply amount in each terminal) 3. Third Embodiment (an example of estimating a remaining power supply amount from a standby time of time information and exchanging an estimated remaining power supply amount between terminals) 4. Modifications A mode for carrying out the present technology (hereinafter, referred to as an embodiment) is hereinafter described. The description will be given in the following order.

1 FIG. is a diagram illustrating an example of an overall configuration of a communication system according to an embodiment of the present technology.

100 200 400 500 600 The communication system includes a plurality of terminals, a base station, a network, a server, and a user application.

100 100 300 100 100 300 100 The terminalis a terminal constituting the communication system. The terminalreceives time information from an artificial satelliteor another terminal, and performs time synchronization on the basis of the time information. Therefore, the terminalincludes a communication unit between the artificial satelliteand the another terminalas will be described below.

400 200 500 600 400 The networkis a network that connects the base station, the server, and the user application. The networkcan be configured by, for example, the Internet.

200 400 100 500 400 100 600 400 100 The base stationis a wireless device that is connected to the networkand performs wireless communication with the plurality of terminals. The serveris connected to the networkand provides overall services for the plurality of terminals. The user applicationis connected to the networkand provides an application executed in the plurality of terminals.

300 100 100 The artificial satelliteis a satellite constituting a global navigation satellite system (GNSS), and transmits a satellite signal to the terminaland the like. The terminalthat has received the satellite signal on a ground can acquire its own position information and the time information on the basis of the satellite signal.

2 FIG. 100 100 is a diagram illustrating an example of types of wireless communication by the terminalaccording to the embodiment of the present technology. It is assumed that each of the plurality of terminalshas the following three wireless communication functions.

100 10 100 100 10 100 Firstly, the terminalhas a wireless communication function for performing terminal-to-terminal communicationwith another terminal. In the first embodiment of the present invention, the terminalexchanges a remaining power supply amount with the another terminal. Furthermore, the time information is distributed from any one of the plurality of terminalsto the another terminal. The terminal-to-terminal communicationis used to implement communication between these terminals. Note that, in this example, four terminals #A to #D are illustrated as the plurality of terminals, but the number of terminals is not limited to four, and any number of terminals may be used.

100 200 100 200 20 Secondly, the terminalhas a wireless communication function with the base station. As will be described below, the terminalincludes, for example, a sensor, and transmits sensor information acquired by the sensor to the base stationas a data signal.

100 30 300 100 30 Thirdly, the terminalhas a wireless communication function for receiving a satellite signalfrom the artificial satellite. The terminalperforms a positioning operation on the basis of the received satellite signalto acquire the position information of its own terminal and the time information.

3 FIG. 100 is a diagram illustrating a configuration example of the terminalaccording to the first embodiment of the present technology.

100 110 120 130 140 150 160 170 181 190 101 103 110 120 130 The terminalin the first embodiment includes a terminal-to-terminal communication unit, a data signal communication unit, a satellite signal reception unit, a control unit, a sensor, a reference time holding unit, a group terminal table, a remaining power supply amount acquisition unit, and a power supply unit. Antennastoare connected to the terminal-to-terminal communication unit, the data signal communication unit, and the satellite signal reception unit, respectively.

110 10 10 110 110 The terminal-to-terminal communicationis a communication unit for performing the terminal-to-terminal communicationwith another terminal. The terminal-to-terminal communicationby the terminal-to-terminal communication unitcan be implemented by, for example, device-to-device communication based on the Bluetooth standard (Bluetooth is a registered trademark). Note that the terminal-to-terminal communication unitis an example of a power supply state determination information communication unit and a time information communication unit described in the claims.

120 20 200 20 120 The data signal communication unitis a communication unit for communicating the data signalwith the base station. For the communication of the data signalby the data signal communication unit, for example, communication in a wide range with low power consumption such as low power wide area (LPWA) is suitable.

130 30 300 30 130 130 The satellite signal reception unitis a communication unit for receiving the satellite signalfrom the artificial satellite. As the satellite signalreceived by the satellite signal reception unit, for example, a satellite signal in a satellite system such as a global positioning system (GPS), GLONASS, or Galileo is assumed. Note that the satellite signal reception unitis an example of a reference signal reception unit described in the claims.

140 100 100 140 The control unitcontrols operation of each unit of the terminal. A specific operation of the terminalwill be described below. Note that the control unitis an example of a representative terminal determination unit described in the claims.

150 100 150 150 100 The sensoris for detecting information of a surrounding environment of the terminal. As the sensor, for example, a temperature sensor, a humidity sensor, a water level sensor, or the like is assumed. Taking a paddy field monitoring system as an application example, it is conceivable to provide a water level sensor for detecting a water level of a paddy field as the sensorin each of the plurality of terminals.

160 100 100 300 100 160 The reference time holding unitis a timer that holds reference time of the terminal. The terminalperforms the time synchronization by receiving the time information from the artificial satelliteor another terminal, and setting the reference time in the reference time holding uniton the basis of the time information.

170 100 100 100 170 170 The group terminal tableis a table for registering the plurality of terminalsthat forms a group that shares the time information. It is assumed that the plurality of terminalsconstituting the communication system has completed grouping before performing a series of operations. Here, the grouping means an operation of registering the plurality of terminalsthat forms a group in the group terminal table. Note that the group terminal tableis an example of a group terminal registration unit described in the claims.

190 100 181 190 190 181 140 30 181 The power supply unitis a battery for supplying power to each unit of the terminal. The remaining power supply amount acquisition unitacquires a remaining power supply amount available in the power supply unitfrom the power supply unit. The remaining power supply amount acquired by the remaining power supply amount acquisition unitis supplied to the control unit. Then, the remaining power supply amount is exchanged between the terminals constituting the group, and the remaining power supply amount is compared in each terminal. As a result, the terminal having the largest remaining power supply amount in the group is determined as the representative terminal. The representative terminal has a role of receiving the satellite signalat the next timing and distributing the obtained time information to the other terminals. Note that the remaining power supply amount acquisition unitis an example of a power supply state determination information acquisition unit described in the claims.

30 300 110 30 30 That is, the terminal having the largest remaining power supply amount among the terminals constituting the group receives, as a representative, the satellite signalfrom the artificial satellite, and the terminal-to-terminal communication unitdistributes the time information to the other terminals. As a result, since only the representative terminal having a relatively large remaining power supply amount performs the reception operation of the satellite signal, the other terminals having a relatively small remaining power supply amount can suppress the power consumption accompanying the reception operation of the satellite signal, and the power consumption among the terminals in the group can be made uniform.

4 FIG. 100 is a flowchart illustrating an example of an operation procedure of the terminalaccording to the first embodiment of the present technology.

100 911 130 30 300 912 In an initial state, setting of the positioning operation of the terminalis on (step S: Yes), the satellite signal reception unitreceives the satellite signalfrom the artificial satelliteand performs the positioning operation (step S). Thereby, the time information is acquired, and the time synchronization is performed.

170 913 181 110 921 At this time, if another terminal is registered in the group terminal table(step S: Yes), the remaining power supply amount acquisition unitacquires its own remaining power supply amount, and the terminal-to-terminal communication unittransmits the remaining power supply amount to the another terminal in the group (step S).

110 923 Furthermore, the terminal-to-terminal communication unitreceives the remaining power supply amount of the another terminal in the group from each terminal (step S). That is, the terminals in the group exchange the remaining power supply amounts with each other.

100 924 925 100 951 952 925 100 953 954 30 300 When receiving the remaining power supply amount from the another terminal, the terminalcompares the remaining power supply amounts (step S). As a result, in a case of determining that its own remaining power supply amount is the largest (step S: Yes), the terminalitself serves as the representative terminal and transmits a reception standby instruction of the time information to the another terminal (step S), and turns on the setting of the next positioning operation of the terminal itself (step S). On the other hand, in a case of not determining that its own remaining power supply amount is the largest (step S: No), the terminalreceives the reception standby instruction of the time information from the representative terminal (step S), and turns off the setting of the next positioning operation of the terminal itself (step S). As a result, the representative terminal that will receive the satellite signalfrom the artificial satellitenext time is determined.

952 954 120 150 200 955 After the next positioning operation is set (step Sor S), the data signal communication unittransmits a sensing data signal acquired by the sensorto the base station(step S).

100 911 170 914 100 916 181 110 922 923 In a case where the setting of the positioning operation of the terminalis off (step S: No), if another terminal is registered in the group terminal table(step S: Yes), the terminalreceives the time information from the another terminal (representative terminal), and perform the time synchronization (step S). Then, the remaining power supply amount acquisition unitacquires its own remaining power supply amount, and the terminal-to-terminal communication unittransmits the remaining power supply amount to the another terminal in the group (step S). Thereafter, the processing in and after step Sis performed.

100 911 170 914 100 915 Note that, in a case where the setting of the positioning operation of the terminalis off (step S: No), if another terminal is not registered in the group terminal table(step S: No), the terminalcannot obtain the time information and thus turns on the setting of its own positioning operation (step S).

5 FIG. 100 is a sequence diagram illustrating an example of an operation of the communication system according to the first embodiment of the present technology. Note that, in this example, the four terminals #A to #D are illustrated as the plurality of terminals, but the number of terminals is not limited to four as described above. The same similarly applies to the following embodiments.

100 100 100 710 100 It is assumed that each of the terminalsoperates independently in the initial state. Therefore, each of the terminalsindependently performs the first positioning operation for time synchronization between the terminals. Therefore, all of the terminals #A to #D receive the satellite signal (). Thereby, each of the terminalsacquires the time information and performs the time synchronization.

181 100 721 110 731 100 After the positioning operation is completed, the remaining power supply amount acquisition unitof the terminalacquires the remaining power supply amount (). Then, the acquired remaining power supply amount is broadcast to the other terminals of the same group through the terminal-to-terminal communication unit(). Thereby, the terminalsof the group exchange mutual pieces of information regarding the remaining power supply amount.

100 740 When the exchange of the information regarding the remaining power supply amount is completed, each of the terminalscompares the remaining power supply amount of the local terminal with the remaining power supply amount of another terminal, and determines whether or not the representative terminal that will perform the next positioning operation is the local terminal ().

100 150 120 750 Each of the terminalstransmits sensing data detected by the sensorthrough the data signal communication unitas a steady operation ().

100 740 811 812 100 The second and subsequent positioning operations for time synchronization between the terminalsare executed on the basis of a result indescribed above. In this example, assuming that the terminal #B is determined to perform the positioning operation as the representative terminal, the terminal #B performs a satellite signal reception operation () and broadcast-transmits the time information to the peripheral terminals (). Meanwhile, the terminals #A, #C, and #D other than the terminal #B do not perform the satellite signal reception operation and wait for the time information from the terminal #B. As a result, each of the terminalsacquires the time information and performs the time synchronization.

181 100 821 110 831 100 After completion of the acquisition of the time information, the remaining power supply amount acquisition unitof the terminalacquires the remaining power supply amount (). Then, the acquired remaining power supply amount is broadcast to the other terminals of the same group through the terminal-to-terminal communication unit(). Thereby, the terminalsof the group exchange mutual pieces of information regarding the remaining power supply amount.

100 840 When the exchange of the information regarding the remaining power supply amount is completed, each of the terminalscompares the remaining power supply amount of the local terminal with the remaining power supply amount of another terminal, and determines whether or not the representative terminal that will perform the next positioning operation is the local terminal ().

100 150 120 850 840 Each of the terminalstransmits the sensing data detected by the sensorthrough the data signal communication unitas a steady operation (). Thereafter, the representative terminal performs the positioning operation according to a determination result in, and the subsequent processing is repeated.

Note that, in a case where the time synchronization cannot be normally completed due to deterioration of a communication state or the like, it is also assumed that the time synchronization is terminated due to timeout. In this case, the processing is continued without waiting for the time synchronization.

181 100 30 30 As described above, in the first embodiment of the present technology, the remaining power supply amounts acquired by the remaining power supply amount acquisition unitare mutually compared between the terminals, and only the representative terminal having a relatively large remaining power supply amount performs the reception operation of the satellite signal. As a result, the other terminals having a relatively small remaining power supply amount can suppress the power consumption associated with the reception operation of the satellite signal, and the power consumption amount among the terminals in the group can be made uniform.

190 190 In the above-described first embodiment, the remaining power supply amount is acquired from the power supply unit, and the representative terminal is determined on the basis of the remaining power supply amount. In this case, the accuracy of the remaining power supply amount obtained from the power supply unitmay not be high, and the representative terminal may not be appropriately determined. Therefore, in the second embodiment, a representative terminal is determined using a standby time required to receive a satellite signal or a time signal. Note that an overall configuration of a communication system is similar to that of the above-described first embodiment, and thus detailed description thereof is omitted.

6 FIG. 100 is a diagram illustrating a configuration example of a terminalaccording to the second embodiment of the present technology.

100 182 181 The terminalin the second embodiment includes a standby time measurement unitinstead of the remaining power supply amount acquisition unitin the first embodiment. Other points are similar to those of the above-described first embodiment, and thus detailed description thereof is omitted.

182 182 182 The standby time measurement unitmeasures the standby time required to acquire the time information. That is, in a case of the representative terminal, the standby time measurement unitmeasures, as the standby time, a time from start of a reception operation of the satellite signal to acquisition of time information through signal processing. Furthermore, in a case of a terminal other than the representative terminal, a time from start of standby for the time information from the representative terminal to acquisition of the time information is measured as the standby time. Note that the standby time measurement unitis an example of a power supply state determination information acquisition unit described in the claims.

110 100 190 100 The measured standby time is distributed to other terminals through a terminal-to-terminal communication unit. As a result, the terminalscompare mutual standby times. It is estimated that a remaining power supply amount of a power supply unitdecreases as the standby time is longer. Therefore, by comparing the standby times between the terminals, a terminal with a small decrease in the remaining power supply amount is determined as the representative terminal.

7 FIG. 100 is a flowchart illustrating an example of an operation procedure of the terminalaccording to the second embodiment of the present technology.

911 916 Since a processing procedure of steps Sto Sis similar to that of the above-described first embodiment, detailed description thereof is omitted.

170 913 182 110 931 916 182 110 932 If another terminal is registered in a group terminal table(step S: Yes), the terminal that has received the satellite signal measures the standby time required to receive the satellite signal and acquire the time information using the standby time measurement unit, and the terminal-to-terminal communication unittransmits the standby time to the another terminal (step S). Furthermore, the terminal that has not received the satellite signal receives the time information from the another terminal (step S), and measures the standby time required to acquire the time information using the standby time measurement unit, and the terminal-to-terminal communication unittransmits its own standby time to the another terminal (step S).

110 933 Furthermore, the terminal-to-terminal communication unitreceives the standby time of the another terminal in the group from each terminal (step S). That is, the terminals in the group exchange the standby times with each other.

100 934 935 100 951 952 935 100 953 954 30 300 When receiving the standby time from the another terminal, the terminalcompares the standby times (step S). As a result, in a case of determining that its own standby time is the shortest (step S: Yes), the terminalitself serves as the representative terminal and transmits a reception standby instruction of the time information to the another terminal (step S), and turns on setting of a next positioning operation of the terminal itself (step S). On the other hand, in a case of not determining that its own standby time is the shortest (step S: No), the terminalreceives the reception standby instruction of the time information from the representative terminal (step S), and turns off the setting of the next positioning operation of the terminal itself (step S). As a result, the representative terminal that will receive the satellite signalfrom the artificial satellitenext time is determined.

Since subsequent processing is similar to that of the above-described first embodiment, detailed description thereof is omitted.

8 FIG. is a sequence diagram illustrating an example of an operation of a communication system according to the second embodiment of the present technology.

100 100 100 710 100 It is assumed that each of the terminalsoperates independently in an initial state, similarly to the above-described first embodiment. Therefore, each of the terminalsindependently performs the first positioning operation for time synchronization between the terminals. Therefore, all of the terminals #A to #D receive the satellite signal (). Thereby, each of the terminalsacquires the time information and performs the time synchronization.

182 100 722 110 732 100 Meanwhile, the standby time measurement unitof the terminalmeasures the standby time required to receive the satellite signal and acquire the time information (). Then, the measured standby time is broadcast to the other terminals of the same group through the terminal-to-terminal communication unit(). Thereby, the terminalsof the group exchange mutual pieces of information regarding the standby time.

100 740 When the exchange of the information regarding the standby time is completed, each of the terminalscompares the standby time of the local terminal with the standby time of another terminal, and determines whether or not the representative terminal that will perform the next positioning operation is the local terminal ().

100 150 120 750 Each of the terminalstransmits sensing data detected by the sensorthrough the data signal communication unitas a steady operation ().

100 740 811 812 100 The second and subsequent positioning operations for time synchronization between the terminalsare executed on the basis of a result indescribed above. In this example, assuming that the terminal #B is determined to perform the positioning operation as the representative terminal, the terminal #B performs a satellite signal reception operation () and broadcast-transmits the time information to the peripheral terminals (). Meanwhile, the terminals #A, #C, and #D other than the terminal #B do not perform the satellite signal reception operation and wait for the time information from the terminal #B. As a result, each of the terminalsacquires the time information and performs the time synchronization.

182 100 822 110 832 100 Meanwhile, the standby time measurement unitof the terminalmeasures the standby time (). Then, the measured standby time is broadcast to the other terminals of the same group through the terminal-to-terminal communication unit(). Thereby, the terminalsof the group exchange mutual pieces of information regarding the standby time.

100 840 When the exchange of the information regarding the standby time is completed, each of the terminalscompares the standby time of the local terminal with the standby time of another terminal, and determines whether or not the representative terminal that will perform the next positioning operation is the local terminal ().

100 150 120 850 840 Each of the terminalstransmits the sensing data detected by the sensorthrough the data signal communication unitas a steady operation (). Thereafter, the representative terminal performs the positioning operation according to a determination result in, and the subsequent processing is repeated.

182 100 30 30 As described above, in the second embodiment of the present technology, the standby times measured by the standby time measurement unitare compared between the terminals, and only the representative terminal having the shortest standby time performs the reception operation of the satellite signal. As a result, the other terminals previously having had a long standby time can suppress power consumption associated with the reception operation of the satellite signal, and the power consumption amount among the terminals in the group can be made uniform.

In the above-described second embodiment, the representative terminal is determined by exchanging the standby time in each terminal between the terminals and comparing the standby times. In contrast, in a third embodiment, a representative terminal is determined by exchanging a remaining power supply amount estimated from a standby time between terminals and comparing the estimated remaining power supply amounts. Note that an overall configuration of a communication system is similar to that of the above-described first embodiment, and thus detailed description thereof is omitted.

9 FIG. 100 is a diagram illustrating a configuration example of a terminalaccording to the third embodiment of the present technology.

100 183 The terminalin the third embodiment includes a power consumption estimation unitin addition to the configuration of the second embodiment. Other points are similar to those of the above-described second embodiment, and thus detailed description thereof is omitted.

183 182 183 30 30 183 The power consumption estimation unitestimates a power consumption amount on the basis of a standby time required to acquire time information. The standby time is measured by the standby time measurement unitsimilarly to the above-described second embodiment. In the third embodiment, the standby time is not exchanged as it is between the terminals, but the remaining power supply amount obtained from the power consumption amount estimated by the power consumption estimation uniton the basis of the standby time is exchanged between the terminals. Thereby, only the representative terminal having a relatively large remaining power supply amount performs a reception operation of a satellite signal, so that the other terminals having a relatively small remaining power supply amount can suppress the power consumption accompanying the reception operation of the satellite signal, similarly to the above-described first embodiment. Note that the power consumption estimation unitis an example of a power supply state determination information acquisition unit described in the claims.

10 FIG. 100 is a flowchart illustrating an example of an operation procedure of the terminalaccording to the third embodiment of the present technology.

911 916 Since a processing procedure of steps Sto Sis similar to that of the above-described first embodiment, detailed description thereof is omitted.

170 913 182 183 110 941 916 182 183 110 942 If another terminal is registered in a group terminal table(step S: Yes), the terminal that has received the satellite signal measures the standby time required to receive the satellite signal and acquire the time information using the standby time measurement unit. Then, the power consumption estimation unitestimates the power consumption amount on the basis of the standby time and acquires the remaining power supply amount. The remaining power supply amount is transmitted to another terminal through a terminal-to-terminal communication unit(step S). Furthermore, the terminal that has not received the satellite signal receives the time information from the another terminal (step S), measures the standby time required to acquire the time information using the standby time measurement unit, estimates the power consumption amount using the power consumption estimation unit, acquires the remaining power supply amount, and transmits the remaining power supply amount to the another terminal through the terminal-to-terminal communication unit(step S).

110 943 Furthermore, the terminal-to-terminal communication unitreceives the remaining power supply amount of the another terminal in the group from each terminal (step S). That is, the terminals in the group exchange the remaining power supply amounts with each other.

100 944 945 100 951 952 945 100 953 954 30 300 When receiving the remaining power supply amount from the another terminal, the terminalcompares the remaining power supply amounts (step S). As a result, in a case of determining that its own remaining power supply amount is the largest (step S: Yes), the terminalitself serves as the representative terminal and transmits a reception standby instruction of the time information to the another terminal (step S), and turns on the setting of the next positioning operation of the terminal itself (step S). On the other hand, in a case of not determining that its own remaining power supply amount is the largest (step S: No), the terminalreceives the reception standby instruction of the time information from the representative terminal (step S), and turns off the setting of the next positioning operation of the terminal itself (step S). As a result, the representative terminal that will receive the satellite signalfrom the artificial satellitenext time is determined.

Since subsequent processing is similar to that of the above-described first embodiment, detailed description thereof is omitted.

11 FIG. is a sequence diagram illustrating an example of an operation of the communication system according to the third embodiment of the present technology.

100 100 100 710 100 It is assumed that each of the terminalsoperates independently in an initial state, similarly to the above-described first embodiment. Therefore, each of the terminalsindependently performs the first positioning operation for time synchronization between the terminals. Therefore, all of the terminals #A to #D receive the satellite signal (). Thereby, each of the terminalsacquires the time information and performs the time synchronization.

182 100 183 723 110 733 100 Meanwhile, the standby time measurement unitof the terminalmeasures the standby time required to receive the satellite signal and acquire the time information, and the power consumption estimation unitestimates the power consumption amount on the basis of the standby time to acquire the remaining power supply amount (). Then, the estimated remaining power supply amount is broadcast to the other terminals of the same group through the terminal-to-terminal communication unit(). Thereby, the terminalsof the group exchange mutual pieces of information regarding the remaining power supply amount.

100 740 When the exchange of the information regarding the remaining power supply amount is completed, each of the terminalscompares the remaining power supply amount of the local terminal with the remaining power supply amount of another terminal, and determines whether or not the representative terminal that will perform the next positioning operation is the local terminal ().

100 150 120 750 Each of the terminalstransmits sensing data detected by the sensorthrough the data signal communication unitas a steady operation ().

100 740 811 812 100 The second and subsequent positioning operations for time synchronization between the terminalsare executed on the basis of a result indescribed above. In this example, assuming that the terminal #B is determined to perform the positioning operation as the representative terminal, the terminal #B performs a satellite signal reception operation () and broadcast-transmits the time information to the peripheral terminals (). Meanwhile, the terminals #A, #C, and #D other than the terminal #B do not perform the satellite signal reception operation and wait for the time information from the terminal #B. As a result, each of the terminalsacquires the time information and performs the time synchronization.

182 100 183 823 110 833 100 Meanwhile, the standby time measurement unitof the terminalmeasures the standby time, and the power consumption estimation unitestimates the power consumption amount on the basis of the standby time to acquire the remaining power supply amount (). Then, the estimated remaining power supply amount is broadcast to the other terminals of the same group through the terminal-to-terminal communication unit(). Thereby, the terminalsof the group exchange mutual pieces of information regarding the remaining power supply amount.

100 840 When the exchange of the information regarding the remaining power supply amount is completed, each of the terminalscompares the remaining power supply amount of the local terminal with the remaining power supply amount of another terminal, and determines whether or not the representative terminal that will perform the next positioning operation is the local terminal ().

100 150 120 850 840 Each of the terminalstransmits the sensing data detected by the sensorthrough the data signal communication unitas a steady operation (). Thereafter, the representative terminal performs the positioning operation according to a determination result in, and the subsequent processing is repeated.

183 100 30 30 As described above, in the third embodiment of the present technology, the remaining power supply amounts estimated by the power consumption estimation unitare compared between the terminals, and only the representative terminal having the largest remaining power supply amount performs the reception operation of the satellite signal. As a result, the other terminals having a small remaining power supply amount can suppress the power consumption associated with the reception operation of the satellite signal, and the power consumption amount among the terminals in the group can be made uniform.

In the above-described embodiments, the representative terminal receives the satellite signal and distributes the obtained time information to the other terminal, but the present invention is not limited to the distribution of the time information. For example, the terminal may not have a communication function for a satellite signal. Furthermore, a system capable of performing asynchronous communication between the terminal and the base station may be used.

Furthermore, the transmission of the sensing data from the terminal to the base station and the communication of the information exchange between the terminals may not be performed separately, and the same communication method may be used.

In the above-described embodiments, LPWA is exemplified as the communication method between the terminal and the base station, but the present invention is not limited thereto, and can be applied to all of wireless communication systems such as mobile phones and wireless local area networks (WLANs).

Note that the embodiments described above show examples for embodying the present technology, and the matters in the embodiments and the matters specifying the invention in the claims have correspondence relationships. Similarly, the matters specifying the invention in the claims and matters with the same names in the embodiments of the present technology have correspondence relationships. However, the present technology is not limited to the embodiments, and can be embodied by applying various modifications to the embodiments without departing from the scope of the present technology.

Furthermore, the procedures described in the above-described embodiment may be considered as a method including a series of procedures and may be considered as a program for allowing a computer to execute the series of procedures and a recording medium which stores the program. As this recording medium, for example, a compact disc (CD), a MiniDisc (MD), a digital versatile disc (DVD), a memory card, a Blu-ray (registered trademark) disc, and the like can be used.

Note that advantageous effects described in the present description are merely examples and are not limited, and other advantageous effects may be provided.

Note that the present technology may also have the following configurations.

a power supply state determination information acquisition unit that acquires power supply state determination information for determining a power supply state of a local terminal; a power supply state determination information communication unit that performs communication for exchanging the power supply state determination information with another terminal; a representative terminal determination unit that determines a representative terminal on a basis of the power state determination information of the local terminal and the another terminal; a reference signal reception unit that receives a reference signal necessary for synchronization and generates time information in a case where the local terminal corresponds to the representative terminal; and a time information communication unit that transmits the time information to the another terminal in the case where the local terminal corresponds to the representative terminal, and receives the time information from the representative terminal in a case where the local terminal does not correspond to the representative terminal. (1) A terminal including:

the reference signal reception unit receives a satellite signal as the reference signal and generates the time information in the case where the local terminal corresponds to the representative terminal. (2) The terminal according to (1), in which

a sensor that acquires a sensing data signal; and a data signal transmission unit that transmits the sensing data signal after synchronization based on the time information is completed. (3) The terminal according to (1) or (2), further including:

the power supply state determination information acquisition unit acquires a value related to a power supply capacity obtained from a power supply of the local terminal as the power supply state determination information. (4) The terminal according to any one of (1) to (3), in which

the value related to the power supply capacity includes a remaining power supply amount of the power supply of the local terminal. (5) The terminal according to (4), in which

the power supply state determination information acquisition unit acquires, as the power supply state determination information, a standby time required to receive the reference signal or the time information within a predetermined period. (6) The terminal according to any one of (1) to (3), in which

the power supply state determination information acquisition unit acquires, as the power supply state determination information, a value obtained by estimating a remaining amount of the power supply of the local terminal on a basis of a standby time required to receive the reference signal or the time information within a predetermined period. (7) The terminal according to any one of (1) to (3), in which

a group terminal registration unit that registers identification information of the another terminal that forms a group, in which a representative terminal determination unit determines the representative terminal on the basis of the power supply state determination information of the local terminal and of the another terminal registered in the group terminal registration unit. (8) The terminal according to any one of (1) to (7), further including:

a base station; and a plurality of terminals, in which the terminal includes a sensor that acquires a sensing data signal; a power supply state determination information acquisition unit that acquires power supply state determination information for determining a power supply state of a local terminal; a power supply state determination information communication unit that performs communication for exchanging the power supply state determination information with another terminal; a representative terminal determination unit that determines a representative terminal on a basis of the power state determination information of the local terminal and the another terminal; a reference signal reception unit that receives a reference signal necessary for synchronization and generates time information in a case where the local terminal corresponds to the representative terminal; a time information communication unit that transmits the time information to the another terminal in the case where the local terminal corresponds to the representative terminal, and receives the time information from the representative terminal in a case where the local terminal does not correspond to the representative terminal; and a data signal transmission unit that transmits the sensing data signal to the base station after synchronization based on the time information is completed. (9) A communication system including:

by a power supply state determination information acquisition unit, acquiring power supply state determination information for determining a power supply state of a local terminal; by a power supply state determination information communication unit, performing communication for exchanging the power supply state determination information with another terminal; by a representative terminal determination unit, determining a representative terminal on a basis of the power state determination information of the local terminal and the another terminal; by a reference signal reception unit, receiving a reference signal necessary for synchronization and generating time information in a case where the local terminal corresponds to the representative terminal; and by a time information communication unit, transmitting the time information to the another terminal in the case where the local terminal corresponds to the representative terminal, and receiving the time information from the representative terminal in a case where the local terminal does not correspond to the representative terminal. (10) A terminal synchronization method including:

10 Terminal-to-terminal communication 20 Data signal 30 Satellite signal 100 Terminal 101 103 toAntenna 110 Terminal-to-terminal communication unit 120 Data signal communication unit 130 Satellite signal reception unit 140 Control unit 150 Sensor 160 Reference time holding unit 170 Group terminal table 181 Remaining power supply amount acquisition unit 182 Standby time measurement unit 183 Power consumption estimation unit 190 Power supply unit 200 Base station 300 Artificial satellite 400 Network 500 Server 600 User application